Tired of reading blog? You can now listen the whole blog from the audio down👇
What are Super Duplex 32550?
A class of stainless steel is called Super Duplex 32550. Because of the almost equal amounts of the two phases austenite (face-centered cubic lattice) and ferrite (body-centered cubic lattice) in their metallurgical structure, these grades are known as austenitic-ferritic grades. This S32550 grade provides good corrosion resistance in a variety of corrosive substances, such as nitric, phosphoric, and sulfuric acids. 32550 also offers exceptional resistance to pitting and crevice corrosion in seawater and other chloride-containing environments, with Critical Pitting temperatures surpassing 50°C. High resistance to abrasion, erosion, and cavitation erosion combined with exceptional flexibility and mark stability at both ambient and sub-freezing temperatures.
The main compositional differences between duplex steels and austenitic stainless steel are greater chromium content (20-28%), higher molybdenum (up to 5%), lower nickel (up to 9%), and 0.05-0.50% nitrogen. Significant cost savings are provided by the low nickel content and good strength (which allows for the use of thinner sections).
They are widely utilized in the petrochemical industry as pipelines and pressure vessels and in the offshore oil and gas industry for pipework systems, manifolds, risers, etc. Duplex steels offer stronger strength in addition to having better corrosion resistance than stainless steels from the 300 series. The minimum 0.2% proof strength for 304 stainless steel is around 280 MPa (41 KSI), for 22%Cr duplex stainless steel it is around 450 MPa (65 KSI); and for the super duplex grade it is at least 550 MPa (80 KSI).
In order to prevent the formation of intermetallic phases which greatly reduces the impact resistance at room temperature and the corrosion resistance, Super Duplex 32550 grades must be cooled as rapidly as possible to room temperature after hot forming. As a result, super duplex grades demand more rapid cooling processes than lean duplex grades and have a wider hot working temperature range.
Application of Super Duplex Steel
Due to their outstanding mechanical qualities and excellent durability, duplex stainless steels are frequently used in construction.
Architecture, Infrastructure, Oil and Gas, Pulp and Paper, Chemical engineering, desalination plants, renewable energy, bus frames, tank trucks,
Engineering: pumps, valves, fittings, springs, etc.
Grades of Super Duplex stainless steel
Typically, these super duplex stainless steel are classified into three categories according to how well they resist pitting corrosion:
Standard Duplex (PREN range 28-38) It is likely the most common type of property nowadays and is representative of the mid-range.
Super Duplex (PREN range 38-45) They provide better strength and corrosion resistance. Users are advised to work with renowned processors because bad processing will lead to subpar performance. Deep-water offshore oil production is one use.
Lean Duplex Grade (PREN range 22-27) In situations where strength is crucial, it can be a huge benefit. Bridges, pressure vessels, and tie bar all exhibit this problem.
